Steel glass seals and steel therefor



United States Fatent C STEEL GLASS SEALS'AND STEEL 'IHEREFGR Freeman J. Phillips, Pittsburgh, and Charles 0. Tan,

McKeesport, Pa., assignors to United States Steel Corporation, a corporation of New Jersey No Drawing. Application October 22, 1952, Serial No. 316,326

6 Claims. (Cl. 75- 123) shattering or placing undue strain on the glass, the coefiicients of expansion of the glass and the metal must be closely matched on cooling, particularly throughout the range of temperature 530 to 30 C. Moreover, for many purposes such as cones for television tubes and the like, it is necessary to form the metal articles in a spinning operation. Due to their ready formability, chromium stainless steels of the 2830% straight chromium type and modified 17% grades of such steel have heretofore been used for such purpose. While such steels are quite satisfactory, they are quite expensive and it is therefore desirable to use cheaper grades of steel. We discovered that stainless steel containing 9.5 to 13.5% chromium can he used for such purpose if modified as hereinafter set forth.

It is accordingly an object of the present invention to provide chromium stainless steels suitable for forming by spinning and for sealing to glass containing less chromium than steels heretofore usable.

it is a further object of the present invention to render stainless steels containing 9.5 to 13.5% chromium suitable for scaling to glass.

The foregoing and further objects of this invention will be apparent from the following invention which is directed generally to chromium stainless steels containing 9.5 to 13.5 chromium.

Steels of this type are readily formable by spinning and are sufficiently oxidation resistant to make them desirable for use in applications requiring that glass be sealed thereto. Moreover, they are considerably cheaper than steels heretofore used. They, however, form austenite upon heating to high temperatures which partially transforms to martensite upon cooling. The accompanying changes in volume, causing an unfavorable coefficient of expansion render them unsuitable for sealing to glass. Also, to be suitable for sealing to glass the steel should have a coefiicient of expansion over the temperature range of 530 to 30 C. of less than 12.5 in./in./ (3., preferably being within the range of about 11.5 to 12.5)(10- in./in./ C.

We have discovered that chromium steels within the range of 9.5 to 12.5% chromium containing less than .10% carbon are generally suitable if they contain at least .50% titanium along with .25 to about 1.00% molybdenum, aluminum within the range of .02 to silicon .10 to 1.00%, manganese .10 to .75% and less than .50% nickel. While the upper limit of titanium is not critical with respect to the purposes of the invention, it is generally maintained below about 1% since larger amounts cause objectionable stringers. Phosphorus and sulphur should be maintained as low as possible. Small quantitles of boron, vanadium and tungsten are not desirable, but may be tolerated. The balance of the alloy is substantially iron.

Steels within the foregoing ranges will generally be ferritic and have a suitable coeflicient of expansion. To ensure the steel being completely ferriti'c, the amounts of the desired elements present should be regulated in accordance with the formula:

Thus if the result is positive, the steel will be completely ferritic Whereas if the result is negative, both ferrite and martensite may be present after quenching from 1200 C.

The following table lists the analyses of a number of steels embodying our invention:

Table I C Mfn P S Si Ni Cr Ti lVIO Al 54 011 015 26 33 9. 66 53 16 B 59 012 017 34 34 13. 30 58 53 15 C 55 008 010 19 39 10. 85 55 11 D 02S 64 009 012 16 39 10. 72 54 84 12 All of these steels were completely ferritic after heat ing to 1200 C. and quenching and the coeificients of expansion on cooling from 530 to 30 C. were within the range of 11.5 to l2.5 10- in./in./ C. Steel A, for example, had a coefiicient of expansion of 12.04, steel C, 12.0 and steel D, 11.9X10 in./in./ C.

As is shown by the following Table II, steels outside the above ranges are unsatisfactory since they were ob served to have both the ferrite and the martensite phases after heating to 1200 C. and quenching:

Table II 0 Mn P S St Ni 01' Ti Mo A1 While we have shown and described several specific embodiments of our invention, it will be understood that these embodiments are merely for the purpose of illustration and description and that various other forms may be devised within the scope of our invention, as defined in the appended claims.

We claim:

1. A stainless steel characterized by being ferritic completely after heating to 1200 C. and quenching, and having a coetficient of expansion of less than 12.5 10 in./in./ C. throughout the temperature range of 530 to 30 C. containing 9.5 to 13.5% chromium, less than .10% carbon, at least .50% titanium, .25 to 1.00% molybdenum, .02 to 30% aluminum, .10 to 1.00% silicon, .10 to .75 manganese and less than .50% nickel, said chromium, carbon, titanium, molybdenum, aluminum, silicon, manganese and nickel being restricted to amounts consistent with the formula 2. A stainless steel characterized by being ferritic completely after heating to 1200 C. and quenching, and having a coefiicient of expansion of less than 12.5 10 in./in./ C. throughout the temperature rangeof 530 to 30 C. containing 9 .5 to 13.5% chromium, less than .10% carbon, at least .50% titanium, .25 to 1.00% molybdenum, .02 to 30% aluminum, .10 to 1.00% silicon, .10 to .75 manganese and less than .50% nickel with the balance substantially iron and residual impurities, said chromium, carbon, titanium, molybdenum, aluminum, silicon, manganese and nickel being-restricted to amounts consistent with the formula 3. A method of forming stainless steel suitable for forming by a spinning operation and sealing to glass, said steel containing 9.5 to 13.5% chromium, less than .10% carbon, at least .50% titanium, .25 to 1.00% molybdenum, .02 to 30% aluminum, .10 to 1.00% silicon, .10 to .75 manganese and less than .50% nickel, comprising melting the steel and controlling the amounts of the foregoing elements therein in accordance with the formula said steel being characterized by being completely *ferritic after heating to 1200 C. and quenching and by having'a coeflicient of expansion of less than 12.5 l in./in./ C. throughout the temperature range of 530 to-30 C.

4. A method. of forming stainless steel suitable for forming by a spinning operation and sealing to glass, said steel containing 9.5 to 13.5% chromium, less than .10% carbon, at least .50% titanium, .25 to 1.00% molybdenum, .02 to 30% aluminum, .10 to 1.00% silicon, .10 to .75 manganese and less than .50% nickel, comprising melting the steel andcontrolling the amounts of the foregoing elements therein in accordance with the formula with the balance substantially iron and residual impurities, said steel being characterized by being completely ferritic after heating to 1200 C. and quenching and by having a coeflicient of expansion of less than 12.5)(10- in./in./ C. throughout the temperature range of 530 to 30C.

5. A glass to steel seal wherein the glass is heated to its fusion point While in direct contact with the steel, the

steel being a ferritic stainless steel containing 9.5 to 13.5% chromium, less than 10% carbon, at least .50% titanium, .25 to 1.00% molybdenum, .02 to 30% aluminum, .10 to 1.00% silicon, .10 to .75% manganese and less than .50% nickel, said chromium, carbon, titanium, molybdenum, aluminum, silicon, manganese and nickel being restricted to amounts consistent with the formula l9.56=a sum greater than unity 7 said steel being characterized by being completely ferritic after heating to 1200 C. and quenching and by having a coefficient of expansion of less than 12.5 l0 in./in./ C. throughout the temperature range of 530 to 30 C.

6. A glass to steel seal wherein the glass is heated to its fusion point while in direct contact with the steel, the steel being a ferritic stainless steel containing 9.5 to 13.5 chromium, less than .10% carbon, at least .50% titanium, .25 to 1.00% molybdenum, .02 to 30% aluminum, .10 to 1.00% silicon, .10 to .75% manganese and less than .50% nickel with the balance substantially iron and residual impurities, said chromium, carbon, titanium, molybdenum, aluminum, silicon, manganese and nickel being restricted to amounts consistent with the formula %Cr+%Si/2+30 %'l'i+lO %Al+ 2.4 %Mo4.27(%Ni+%Mn/2 %C)- l9.56=a sum greater than unity said steel being characterized by being completely ferritic after heating to 1200 C. and quenching and by having a coefiicient of expansion of less than 12.5 X10- in./in./ C. throughout the temperature range of 530 to 30 C.

References Cited in the file of this patent UNITED STATES PATENTS 1,947,417 Holst Feb. 13, 1934 2,024,561 Becket Dec. 17, 1935 2,670,572 Smith Mar. 2, 1954 FOREIGN PATENTS 730,161 Germany Jan. 7, 1943 OTHER REFERENCES Metal Progress, vol. 52, July to December publications, pages 94 to 96, and 102. Published by the American Society for Metals, Cleveland, Ohio. 

1. A STAINLESS STEEL CHARACTERIZED BY BEING FERRITIC COMPLETELY AFTER HEATING TO 1200* C. AND QUENCHING. AND HAVING COEFFICIENT OF EXPANSION OF LESS THAN 12.5X10**6 IN./IN./* C. THROUGHOUT THE TEMPERATURE RANGE OF 530* TO 30* C. CONTAINING 9.5 TO 13.5% TITANIUM, MIUM, LESS THAN .10% CABON, AT LEAST .50% TITANIUM, .25 TO 1.00% MOLYBDENUM, .02 TO .30% ALUMINUM, .10 TO 1.00% SILICON, .10 TO .75% MANGANESE AND LESS THAN .50% NICKEL, SAID CHROMIUM, CARBON, TITANIUM, MOLYBDENUM, ALUMINUM, SILICON, MANGANESE AND NICKEL BEING RESTRICTED TO AMOUNTS CONSISTENT WITH THE FORMULA 